1. Field of the Invention
This invention relates to a dispensing device for simultaneously dispensing a multiplicity of predetermined quantities of liquid. Such dispensing devices are useful, for example, in testing where it is necessary to supply predetermined quantities of liquid reagent to separate vessels. This invention also relates to apparatus for recording a multiplicity of reactions effected simultaneously in separate vessels. The invention is particularly, though not exclusively, concerned with improving the efficiency of biochemical analyses where large numbers of biochemical tests are required to be conducted speedily and efficiently.
2. Description of the Prior Art
Various devices have been proposed for dispensing liquid into a number of vessels. For example, it has been proposed to dispense liquid by use of a row of pipettes each having a plunger associated therewith, the plungers being connected to a common operating device which may be operated mechanically or manually to draw liquid into the pipettes and subsequently to dispense it. Examples of such devices are disclosed in U.S. Pat. Nos. 3,568,735 to Lancaster (Class 141/238) and to Sekine (Class 73/423); 4047438.
It has also been proposed in European patent application No. EP 80 30 3132, filed Sept. 5, 1980, Dynatech AG (Int. Cl. G 01 N 21/76), to utilize a dispensing device in which liquid feed is effected using a multichannel peristaltic pump.
The above types of dispensing devices are both relatively expensive and not readily adaptable for use in dispensing liquid into a very large number of vessels.
It has further been proposed in U.S. Pat. No. 3,696,971 to Madin (Class 222/183) to arrange for the upper ends of a number of pipettes to open into a large chamber which is subjected to reduced pressure to fill the pipettes with liquid which is then pressurized to dispense the liquid from the pipettes. A similar principle is employed in U.S. Pat. No. 3,982,438 to Byrd (Class 73/425.6) to fill the pipettes and effect dispensing except that, in this case, negative and positive pressure is applied to the pipettes through the intermediary of a flexible diaphragm. The Applicants have found that such devices which rely on the application of negative and positive pressures to effect aspiration and dispensing are expensive and/or do not consistently dispense precisely controlled volumes of liquid.